What if the hell fire, brimstone, death and demons in death metal and its multifarious subgenres (grindcore, black metal, Satanic metal, Gothic metal, deathgrind, goregrind, pornogrind, metalcore, etc.) were actually real? What if – as Mary Whitehouse, countless Christians and a million parents always feared – this “devil’s music” actually had the power to conjure up actual demonic forces? The idea is certainly nothing new: ever since Screaming Lord Sutch recorded a blood-curdling cover of “Jack the Ripper” in 1963 – coincidentally, the year Mario Bava’s Black Sabbath, which gave one of the UK’s biggest heavy metal bands its name, was released – horror and heavy metal (as it would later become known) have walked hand in leather-gloved hand for more than 50 years.

As early as 1974, Brian De Palma’s Phantom of the Paradise combined hard rock and horror (of a kind), but it wasn’t until the 1980s – when hair metal reached its zenith (or nadir, depending on your viewpoint), and the arrival of VHS made cheesy low-budget horror movies not only possible, but highly profitable – that “metalsploitation” movies began to explore the possibilities of rock-y horror. 1980’s Terror on Tour, for example, trails Kiss-style rock band The Clowns as they tour America, shredding more than guitars. In Rock ‘n’ Roll Nightmare (1987), Jon Mikl Thor (frontman for metal band Thor) finds Satan himself thwarting his efforts to record a new album. And who could forget Rocktober Blood (1988), in which the lead singer of the titular rock band returns from the dead to wreak bloody vengeance on his former bandmates, fans, and anyone else who gets in his way.

Despite the best efforts of musicians-slash-horror fans Dee Snyder (Strangeland), Rob Zombie (House of 1,000 Corpses, etc.) and, well, Slash (Nothing Left to Fear), it’s been a while since we’ve been treated to a horror film in which heavy metal takes centre stage. But now, seemingly out of nowhere (but actually New Zealand), comes writer-director Jason Lei Howden’s DEATHGASM (which has to be written in capital letters, because as one of the characters points out, “lower case is for pussies”), which for filmmaking flair, gloopy gore and horrific hilarity looks set to be the biggest crowd-pleaser of this year’s FrightFest. The last time I had this much fun watching a horror film was nearly thirty years ago, watching Evil Dead II.

Plot-wise, DEATHGASM recalls 1986’s Trick or Treat (heavy metal fan summons murderous glam rocker by playing a cassette backwards) and the following year’s The Gate (heavy metal fans, including a young Stephen Dorff, summon demons by playing a record backwards) – with a batsqueak of Black Roses (1988) and Shock ‘Em Dead (1991) thrown in. Metalhead Brodie (Milo Cawthorne) is having a FML moment: his meth-head mum’s been incarcerated (“for trying to suck off a Santa in a crowded shopping mall”), so he’s been sent to the aptly-named suburban wasteland Greypoint to live with his Bible-bashing uncle and Brodie-bashing cousin. Bullied by the jocks, wooed by the nerds, and all but invisible to local hottie Medina (Kimberley Crossman), things look bleak for Brodie – until he decides to start a death metal band with would-be D&D buddies Dion (Sam Berkley) and Giles (Daniel Cresswell) and fellow metalhead Zakk (James Blake). Its name? DEATHGASM. “All in capitals,” explains Zakk. “Lower case is for pussies!”

A few rehearsals and one hilarious, “corpse-paint” music video later, Brodie has got Medina’s attention… but when he and Zakk discover the sheet music to a Satanic song by legendary death metal band Haxan Sword, they unleash the darkest and most diabolical forces since Ash read a few passages from the Book of the Dead. Before long, the entire town is possessed by demons, forcing the “axe”-playing Brodie and his band (and Medina, quite the badass demon huntress herself) to weapon up and take on the evil hordes – with, it must be said, the kind of relish you’d expect from followers of bands with names like Extreme Noise Terror, Napalm Death, Ripping Corpse and Dance Club Massacre.

DEATHGASM’s plot may bear a passing resemblance to earlier, inferior “heavy metal horror” movies, but in all other respects it is full of surprises; chiefly that Howden’s feature debut gets so many things 100% right first time. Sure, he’s an experienced visual effects artist, having worked (in relatively minor capacities, and often uncredited) on The Avengers, Prometheus, The Hobbit films and The Wolverine, but that’s no reason to think that he would be able to nail the notoriously tricky comedy-horror thing, let alone things like dialogue, storyboarding, casting, creature design, costumes, directing actors, editing, practical and digital effects (and, crucially, well-judged combinations thereof) and every other aspect of the film that works so well. (Not to take anything away from Howden’s crew, but the director does oversee all this stuff.) On a first viewing, your jaw may hit the floor over the many imaginative kills, each executed in all its gory glory; on a second, you’ll find yourself marvelling at Howden’s attention to detail in other creative and technical areas, such as the lengths to which Howden goes to get certain elaborate shots (you’ll know the ones I mean), only to shred them in the editing room for the sake of pace. And what a pace it is. Once the really heavy shit hits the heavy metal fans, the action barely lets up for a second. There’s literally so much to see, you’ll want to watch it again as soon as it’s over.

In 1987, Peter Jackson put New Zealand on the horror movie map with Bad Taste. It was good, but clearly the work of an enthusiastic amateur – and look where Jackson is today. Given the precocious skills that fellow New Zealander Howden displays in his own feature debut, one can only imagine the delights to come from this exciting and inspiring new filmmaker.

Arguably the most insanely enjoyable debut since Sam Raimi’s The Evil Dead – yes, really – DEATHGASMis nothing short of an instant classic. Assuming, of course, that you have the stomach for the gory stuff.